Container closures or caps are generally lined with a thin metal foil or paper liner before assembly onto the container. There are many types of machines for applying liners to caps. Most machines operate by feeding a cap into a cap-lining machine where a paper insert is punched from a web of liner paper and then tamped into the cap, and most line caps at an incredible rate. The machines often fail, however, creating downtime that can result in production and supply issues.
In many early cap-lining machines, the caps were mechanically fed into the cap-lining machine, such as by a stuffer rod which pushed a set of caps into a channel toward the machine. A line of caps thus forcefully moved through the channel, the stuffer rod pushing the line forward toward a tamping location.
New cap construction techniques, however, rendered many of these past machines, such as those reliant on stuffer rods, undesirable. Cap manufacturers increasingly use softer and lighter materials to save costs. While the use of less material in a cap does save on manufacturing costs, it creates a thinner, more pliable cap. When such caps are advanced through a narrow channel, as by a stuffer rod, they frequently deform under the stuffing force and then bind within the channel. The caps may be permanently deformed, in which case the liner inserts cannot be properly applied to the caps, or the caps may actually crack, in which case the liner insert can be applied but will of course be wasted when the cap is rejected. When a cap binds within the channel, the upstream caps are prevented from moving forwardly, and the downstream caps may fail to advance. As more caps are fed or stuffed into the channel, the upstream caps can be forced into the stuck cap, which may cause them to be jammed, deformed, or broken as well. While the cap-lining machine may detect that a new cap has not been presented to the tamping location, upstream caps may continue to be damaged, and a worker must shut the machine down, remove the bound cap, inspect the machine for damage, inspect and remove damaged upstream caps from the system, and restart the machine.
The lighter construction of caps presents problems for holding the caps in position in preparation for tamping as well. In the past, caps were placed in the tamping location under the punch or tamp and held in alignment with the tamp by a biased or sprung mechanism acting on the cap from the sides, such as gripping jaws. After the cap had been lined, the cap would be released from the mechanism and allowed to move forward. Caps would frequently be squeezed out of the mechanism at high speeds, which could cause the caps to fly out of the machine, move too quickly for downstream daisy-chained operations, or jam in the downstream channel. Further, the mechanism could deform or even crush the cap while it was being held in place for lining. This would result in an improperly-fit liner insert, caps moved out of alignment from the tamp, smashed caps, jammed tamping locations, and other problems which caused mechanical damage to the cap-lining machine and could require the cap-lining machine to be shut down and repaired.
Old machines were also dangerous to users. Most of the mechanical assemblies that would stop the feed of the liner paper when a cap was missing used heavy, complex, moving parts. Machines that mechanically moved caps into place, such as by large rotating tables, cam-driven racks, or stuff rods, usually employed heavy, rugged, metal fixtures. The stuffer rods, for instance, were frequently driven by clutched gear assemblies capable of producing a large amount of torque and force to push a long line of caps toward and through a cap-lining machine. Moving parts such as these presented safety hazards to errant fingers and limbs.
An improved and safer system and method for advancing caps into a tamping location is needed.